Beyond Cholesterol

Cholesterol is a household word, synonymous with coronary artery disease. But a growing body of research shows that this fat-like substance in your blood is just the tip of the iceberg. Scientists have learned that other substances may give you and your doctor new clues about your heart disease risk. And that's good news. Coronary heart disease, in which fatty deposits build up in your arteries, is the nation's top killer.

There are more predictors of coronary artery disease and the search continues for knowledge of these risk factors. Your doctor can look at a more complete risk pattern with the new findings in mind. Even if you do not have coronary artery disease, the new predictors can provide a more complete and aggressive plan for reducing the incidence. "This is very much a work in progress," says Stephen R. Devries, M.D., a cardiology and internal medicine specialist in Chicago. "We can now identify more heart disease triggers than ever before, but there's a lot to be learned."

How can you and your doctor use the findings? If you don't yet have heart disease, the best way is to look at the whole picture, says Dennis L. Sprecher, M.D., a cardiologist in Cleveland. "What these newer predictors can do," he says, "is provide us with a sense for how aggressive we should be in treating those things we already know how to treat."

Current predictors of coronary artery disease include too much LDL ("bad") cholesterol and not enough HDL ("good") cholesterol. If your levels are abnormal data on the new predictors could influence the decision for more intense treatment.

Potential new predictors

Homocysteine

Homocysteine is an amino acid, a part of protein which seems to be toxic to the cells that line the arteries. This toxicity seems to influence the disruption of plaque. If plaque ruptures, a clot forms, blocking vital blood flow. If this takes place in an artery that supplies blood to the heart, a heart attack occurs. Scientists are studying whether B vitamins—B12, pyridoxine, and folic acid, all of which appear to lower levels of homocysteine in the blood—may help treat high levels of the amino acid. So far, the American Heart Association recommends only that you take in 400 mcg daily of folic acid for its general health benefit. Experts don't recommend routine blood tests for homocysteine unless you have other heart-disease risk factors, or unless you have heart disease but no known risk factors. Occasionally, your healthcare provider may want to check your homocysteine level if your close family members have high homocysteine levels and premature heart disease. Your homocysteine level could provide a clue to your risk of developing heart disease.

Triglycerides

Triglycerides are no longer the new kid on the block, but many people still don't realize their importance. They are your body's most common form of fat and the main source of stored energy. Your liver makes triglycerides and cholesterol from food. Doctors should view high triglyceride levels as a warning sign.

Diet and exercise affect triglycerides, just as they do cholesterol. Obesity, inactivity, and high-sugar foods can cause special trouble. If lifestyle changes, like a low-fat diet and exercise, don't lower triglycerides, Dr. Devries says, drugs such as statins and fibrates may help, along with the vitamin nicotinic acid, a specific form of niacin. (Other forms of niacin do not affect triglyceride levels.) Labs check triglycerides as part of a full lipid study that also measures HDL and LDL. Talk with your doctor if your level is high.

C-reactive protein

Your C-reactive protein (CRP) level rises if there's inflammation in your body. Scientists think chronically high levels might predict inflammation in blood vessels. However, even with a bit of a cold, CPR levels will rise.

Testing is very sensitive but not very specific. The AHA does not recommend checking everyone's CRP level. For people with risk factors for heart disease, however, a CRP level may help a physician decide whether to be more aggressive with treatment to reduce or eliminate risk factors for heart disease. Levels above 3 are considered high. Studies show statins may lower CRP.

Lp(a)

Lp(a) is a fat-carrying particle made up of LDL and protein. A high level of Lp(a) is a risk factor for developing premature atherosclerosis. Scientists agree that your Lp(a) level is set mainly by genetics, so people with a family history of heart disease may have high levels. Knowing this may help doctors decide how aggressively to treat other risk factors, such as high LDL cholesterol.

Like high cholesterol, high Lp(a) levels can also be treated with statin drugs and niacin, but doctors don't yet know if lowering your Lp(a) level cuts your heart-disease risk. Your doctor would likely order an Lp(a) blood test only if you have other serious risk factors for heart disease.

Cholesterol: Still the top danger sign

A high level of cholesterol in the blood is still the top heart disease predictor. A report from the National Heart, Lung, and Blood Institute urged these changes in cholesterol screening and treatment:

If you are 20 or older and of average risk for heart disease, you should have a full lipid profile at least every five years. This test is done after fasting and measures total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides. LDL is the lipoprotein that carries the form of cholesterol that builds up in the arteries. HDL is the lipoprotein that carries cholesterol that is being removed from the body, which keeps it from building up on the walls of arteries

Doctors should treat certain people at risk more aggressively with drugs. The LDL level at which treatment with drugs is advised depends on whether you have other risk factors. People with two or more of the following risk factors are considered at higher risk: an HDL below 40 mg/dL; high blood pressure; a family history of early heart disease (a first-degree relative with heart disease before age 55 if a man, or before 65 if a woman); diabetes; smoking; and age (45 or older if a man, or 55 or older if a woman).

The metabolic syndrome—a combination of abdominal obesity, high triglycerides, low HDL, high blood pressure, and a high blood sugar level—also puts you at risk.

If you're at risk for heart disease, you should make important lifestyle changes. You should cut saturated fats to 7 percent of your total daily calories, lower cholesterol in your diet to less than 200 mg a day, eat more soluble fiber and foods with plant stanols or sterols (found in some margarines and salad dressings), stick to a healthy weight, and make exercise a habit.

You should learn your risk level. Experts have set up four risk categories. Your doctor can work out your level with a risk assessment tool based on blood tests, blood pressure, and history of smoking.

Risk predictor*

Ideal number

Total cholesterol

Below 200 mg/dL

HDL cholesterol

Above 60 mg/dL

LDL cholesterol

Below 100 (depending on other risks) mg/dL

Triglycerides

Below 150 mg/dL

*You should not eat or drink anything but water for nine to 12 hours before these tests.